Question

We want to remove tons of obsolete data in a table, but this will lock table for a long while. Is is possible to use Cursor to delete, says, one hundred records per transaction in a while-loop ?

And where can I refer to the example?

Answer 1

Something like this:

DECLARE @stillgoing bit;
SET @stillgoing = 1;

WHILE @stillgoing = 1
BEGIN
  DELETE TOP (100) YourTableName
  WHERE IsObsolete = 1;

  IF @@ROWCOUNT = 0
      SET @stillgoing = 0;

  CHECKPOINT /* Will encourage the log to clear if it's in Simple recovery model */
END

Edit: This will only work in SQL 2005 and on. As we’ve just learned it’s SQL 2000, this code instead:

DECLARE @stillgoing bit
SET @stillgoing = 1

SET ROWCOUNT 100

WHILE @stillgoing = 1
BEGIN
  DELETE YourTableName
  WHERE IsObsolete = 1

  IF @@ROWCOUNT = 0
      SET @stillgoing = 0

  CHECKPOINT /* Will encourage the log to clear if it's in Simple recovery model */
END

And… Simple Recovery Model means that the log will truncate on checkpoints, rather than only when the log is backed up.